The use of electric power-steering apparatuses is widely spread as a steering apparatus for applying a steering angle to the steered wheels of an automobile, and that uses an electric motor as a drive source to reduce the steering force. FIG. 10 illustrates an example of a conventional electric power-steering apparatus. The directions in the following explanation are all directions when the steering apparatus is assembled in a vehicle.
In the case of the structure illustrated in FIG. 10, a steering shaft 2 is supported by way of a rolling bearing (not illustrated in the figure) on the inside of a cylindrical steering column 1 that is supported by the vehicle body so as to be able to freely rotate. A steering wheel 3 is fastened to the portion on the rear end section of the steering shaft 2 that protrudes from the opening section on the rear end of the steering column 1. The portion on the front end section of the steering shaft 2 that protrudes from the opening on the front end of the steering column 1 is connected to the rear end section of the intermediate shaft 5 by way of a universal joint 4a. Furthermore, the front end section of the intermediate shaft 5 is connected to the input shaft (pinion shaft) 7 of the steering gear unit 6 by way of another universal joint 4b. 
As the steering wheel 3 rotates, this rotation is transmitted to the input shaft 7 by way of these members, and pushes and pulls a pair of left and right tie rods 8 by way of the steering gear unit 6, which applies a steering angle to a pair of left and right steered wheels according to the operation amount (steering angle) of the steering wheel 3. Particularly, in the case of the first example of conventional structure, by applying auxiliary power to the steering shaft 2 by an electric motor 9 that is supported on the front end section of the steering column 1, the force necessary for turning the steering wheel 3 is reduced.
FIG. 11 illustrates an example of specific structure of the major parts of an electric power-steering apparatus that is disclosed in JP 9-20252 (A). In the case of this structure, in order for the electric motor 9a to apply an auxiliary force to the steering shaft 2a, a cylindrical transmission shaft 11 is supported inside a housing 10 that is fastened to the front end section of the steering column 1a so as to be able to rotate, and the rear end section of this transmission shaft 11 and the front end section of the steering shaft 2a are connected by way of a torsion bar 12 so as to be able to transmit torque. Moreover, a worm wheel 13 that is fastened to the outer circumferential surface of the middle section of the transmission shaft 11 is made to engage with a worm 15 that is fastened to the output shaft 14 of an electric motor 9a so as to be able to apply auxiliary power from the electric motor 9a to the transmission shaft 11. Furthermore, in order to measure the torque that is applied to the steering shaft 2a, a torque sensor 16 is arranged around the transmission shaft 11. A harness 19 is connected by way of a connector 18 to the circuit board 17 that is connected to this torque sensor 16, and measurement values that indicate the direction and size of the torque that are outputted from this torque sensor 16 are inputted to a controller (ECU) (not illustrated in the figure).
In the case of this structure, the housing 10 is composed of a worm wheel housing section 48, a torque sensor housing section 49, a circuit board housing section 50 and a worm housing section 51. The worm wheel housing section 48 is an approximate circular disk shape that is arranged so as to be concentric with the steering column 1a, and houses the worm wheel 13 on the inside thereof. The torque sensor housing section 49 is provided adjacent to the rear side of the worm wheel housing section 48, and having a smaller diameter than the worm wheel housing section 48, houses the torque sensor 16 on the inside thereof. The circuit board housing section 50 is provided above the torque sensor housing section 49, and houses the circuit board 17 on the inside thereof. Furthermore, the worm housing section 51 has an approximate cylindrical shape that is arranged in a twisted position with respect to the steering shaft 2a, and houses the worm 15 on the inside thereof. The connector 18 is located above the circuit board housing section 50. Moreover, the worm wheel housing section 48 and the torque sensor housing section 49 cover the worm wheel 13 and the torque sensor 16 with minimum volume. Therefore, the outer circumferential surfaces of both the worm wheel housing section 48 and the torque sensor housing section 49 are formed into a circular shape along the shape of the worm wheel 13 and the torque sensor 16.
In the case of this structure, it is possible to control the direction and amount of current flowing through the electric motor 9a (the drive state) based on measurement values from the torque sensor 16, so it is possible to adequately reduce the force necessary for turning the steering wheel 3 (see FIG. 10) that is fastened to the rear end section of the steering shaft 2a. However, before or after the electric power-steering apparatus is assembled in the vehicle, there is the possibility that the following problems may occur.
That is, in the case of this structure, when the electric power-steering apparatus is temporarily placed on the floor or the like before being assembled in the vehicle, there is a possibility that the connector 18 may come in contact with the floor together with the end section of the harness 19. This connector 18 is often made using synthetic resin or the like, so in the case that it comes in contact with the floor, there is a possibility that damage could occur such as part being scratched, or some of the internal wiring could be cut. A unit having this kind of damaged connector 18 must be discarded as a defective unit, so it causes an increase in cost.
Moreover, in the case of this structure, there is a possibility that other parts other than the connector 18 that is used in connecting to the circuit board 17 could be damaged when the electric power-steering apparatus is temporarily placed on the floor or the like. In order to maintain the reliability of electrical supply connectors for supplying electric power to the electric motor 9a for which larger drive electric power is needed compared with the other electric components, often large-capacity connectors are used. Such large connectors when simply placed near the worm wheel housing section 48, due to the shape of the outer circumferential surface of the worm wheel housing section 48 being a circular shape, part of these connectors protrudes from the worm wheel housing 48 and could be easily damaged.
In addition, after the electric power-steering apparatus has been assembled in the vehicle, the connector 18 is placed on the upward side of the housing 10 (top side in FIG. 11), and is arranged in a narrow empty space between the housing 10 and a member on the vehicle side such as a steering support. Furthermore, the work of connecting the harness 19 to the connector 18 is normally performed from the driver seat side, so for the worker performing this connection work, the connector 18 is hidden behind the housing 10. Therefore, performing the work of connecting the harness 19 to the connector 18 after the electric power-steering apparatus has been assembled in the vehicle is inferior in work characteristics, and it causes an increase in cost.
On the other hand, it is feasible to complete the connection work before the electric power-steering apparatus has been assembled in the vehicle. However, when one group of electrical components that are electrically connected by way of a connector is arranged on both the electric power-steering apparatus side and the vehicle side, in order to perform the connection work before assembly, the length of the harness that connects to the connector must be sufficiently longer than the originally required length. Therefore, together with causing costs and weight to increase, the harness gets in the way, and there is a possibility that the ease of performing the work of assembling the electric power-steering apparatus will decrease. Depending on the arrangement of the electrical components, there may be cases wherein performing the connection work in advance before assembling the apparatus in the vehicle could be difficult or disadvantageous.